Multi-contact selector switch for high currents



Sept. 30, 1969 w. L. DEXTER 3 70,

MULTI-CONTACT SELECTOR SWITCH FOR HIGH CURRENTS Filed Feb. 7; 1968 2 Sheets-Sheet 1 I I J 68 INVENTOR.

WARREN L. DEXTER BY I IQ I /K-( W ATTORNEY.

Sept. 30, 1969 w. L. DEXTER 3,470,503

MULTI-CONTACT SELECTOR SWITCH FOR HIGH CURRENTS Filed Feb. 7, 1968 2 Sheets-Sheet 2 INVENTOR.

O WARREN L DEXTE'R ATTORNEX United States Patent O 3,470,503 MULTI-CONTACT SELECTOR SWITCH FOR HIGH CURRENTS Warren L. Dexter, Orinda, Califl, assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Feb. 7, 1968, Ser. No. 703,630 Int. Cl. H01h 3/02, 67/14 US. Cl. 335-69 6 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The present invention relates generally to electrical switches and more particularly to switches for handling currents in the order of 1000 to 2000 amperes. The invention described herein was made in the course of, or under Contract W7405eng48 with the Atomic Energy Commission.

The switch of the present invention has been designed to obtain a large current carrying capacity in a unit of small size, low cost, and which is remotely controllable. In some respects, the construction of the switch is similar to that of a current reversing switch as described in US. Patent No. 3,263,145, issued July 26, 1966 to the present inventor. However, the present invention is used for a differing type of switching function and utilizes differing switch positioning control means than in the previous switch.

High current switches are used, for instance, to control large direct currents for energizing large magnets, or for electroplating operations.

Summary of the invention The present invention is a switch which has the general physical configuration of a fiat insulative sheet or panel to which stationary electrical contacts are aflixed. A motor driven lead screw passes transversely through the center of the panel and, depending upon the direction of rotation, causes one or more bridging contacts to advance toward or retract from the contacts on the panel. The bridging contacts have no external connections but, when positioned against a pair of the contacts on the panel, electrically bridge between the contacts. To efiect switching, the bridging contacts are retracted from the panel by rotation of the lead screw, repositioned, and advanced toward the panel to bridge between another selected pair of stationary contacts. To enable the switch to be controlled remotely, the means for positioning the bridging contacts utilizes solenoids which are activated according to the switch position desired.

The selector switch has a common contact, a plurality of circuit contacts disposed adjacent the common contact and spaced therefrom by a gap, the circuit contacts and the common contacts being in a single plane, at least one bridging contactor having a width greater than the.

gaps, means consecutively withdrawing and advancing the contactor from and toward the gaps in a direction transverse to the plane, the contactor electrically bridging across a selected one of the gaps from the common contact to one of the circuit contacts when the contactor 3,470,503 Patented Sept. 30, 1969 is fully advanced, and means aligning the bridging contactor with a selected one of the gaps when the contactor is withdrawn from the circuit contacts and the common contact.

It is an object of the present invention to provide a remotely controllable current transfer switch.

It is another object of the present invention to provide a current transfer switch of relatively small size and low cost.

It is another object of the present invention to provide a current transfer switch capable of handling currents exceeding 1000 amperes.

Brief description of the drawing The invention together with further objects and advantages thereof will be best understood by reference to the accompanying drawing of which:

FIGURE 1 is a general side view of a switch according to the invention,

FIGURE 2 is a broken out end view taken at line 22 in FIGURE 1,

FIGURE 3 is an end view taken at line 3-3 in FIG- URE l, and

FIGURE 4 is a drawing of the control circuitry for the switch.

Description of a preferred embodiment In the embodiment of the invention to be described, simultaneous switching is provided for two separate circuits, each of two common circuits being connectable to one of four selected circuits. With such a switch, for instance, both sides of a power supply line can be selective- 1y switched across any one of four loads.

Referring now to FIGURES 1, 2 and 3 there is shown a switch 11 having spaced apart first and second end pieces 12 and 13. Bolts 14 physically join the end pieces 12 and 13, spacing sleeves 16 and 17 being disposed around the bolts 14 between the end pieces. The bolts 14 pass through holes 18 in an insulative terminal board 19, the sleeves 16 and 17 holding the terminal board between the end pieces 12 and 13.

As best shown in FIGURE 2, eight circuit contacts 21, individually identified by letters a to d and aa to dd, are disposed radially outwardly with respect to the center 20 of terminal board 19 and are afiixed to the board by bolts 22. A pair of common contacts 23a and 23m: are also afiixed to the terminal board 19, the common contacts being shaped at an outer end 24 to extend radially oil the board and having a generally curved configuration at an inner end 26, the inner end of each common contact having an arcuate form and extending slightly less than half the distance around the center 20 of board 19. The outermost edge of the curved inner end 26 of the common contacts 23 is separated by gaps 27 from the ends of radial circuit contacts 21.

A motor mount base 28 is afiixed to the first end piece 12 by bolts 29. A motor 31 drives a threaded lead screw 32 which passes through first end piece 12 and terminal board 19, with the end of the screw being supported by a bearing 33 on second end piece 13. The axis of the screw 32 coincides with the center 20. A disc 34, generally made of some insulative material, is threaded onto the screw 32, as in the manner of a nut on a bolt. However, it is essential that the threading on the disc 34 provide a degree of friction so that when the screw 32 is rotated, the disc will always turn with the screw unless restrained by an external positioning means described later. One means by which such friction may conveniently be obtained is described in the above-mentioned US. Patent No. 3,263,145 wherein a nylon (polyamide) slug on a rotatable disc is pressed against the threads of a lead screw by a spring. Electrically conductive bridging contacts 36 are each supported on a shaft 37 which passes through suitable holes 38 in the disc 34. In the embodiment of the invention shown, the bridging contacts are used in sets of two with two sets being provided at a 180 spacing around the disc 34. A spring 39 on each shaft 37 is compressed between the bridging contact and the disc 34, urging the bridging contacts toward the terminal board 19. A pin 41 through the end of shaft 37 protruding through the disc 34 secures the shaft to the disc. Each set of bridging contacts is disposed so that it is aligned with the gaps 27 and can electrically bridge across a gap when pressed against the contacts 23 and 21.

In the operation of the switch, the bridging contacts 36 are retracted from contacts 21 and 23 by moving the disc 34 transversely away from the contacts, the disc then being repositioned and advanced back toward the contacts 21 and 23, the bridging contacts then coupling a dilfering contact 21 to contact 23.

When the bridging contacts 36 are to be retracted and repositioned, the motor 31 is activated and lead screw 32 is rotated (clockwise as seen in FIGURE 2). Since each set of bridging contacts 36 is initially pressed against a contact 23 and one of the contacts 21, the disc 34 cannot turn with the lead screw 32. Therefore, the disc 34 is caused to move away from the contacts 21 and 23 along the screw 32. When the bridging contacts 36 are no longer forcefully pressed against the contacts 21 and 23, the disc 34 turns with the screw 32. The disc 34 rotates a part of one turn until stopped by either of two means. In the first means, a pin 42, secured to the disc 34, contacts a stop pin 43 which protrudes from the second end pieces 13. The disc 34 then continues to be retracted from the contacts 21 and 23 until the edge of disc 34 contacts the switching element of a motor reversing microswitch 44. Through circuitry shown in FIGURE 4, the direction of rotation of motor 31 is reversed and the disc 34 is thus urged to correspondingly rotate, rotating pin 42 away from stop 43. The disc 34 rotates a portion of a turn and is stopped by a second locking nieans which engages the disc as is described next.

In the embodiment of the invention being described, there are four circuit contacts 21, a to a and aa to dd, associated with each of the contacts 23, a and aa, respectively; thus there are four possible switch positions at which the bridging contacts 36 may be selectively positioned. Four solenoids 46, a to d, two of which are shown in [FIGURE 1, are affixed to the motor mount base 28. Correspondingly lettered components are related in that, for instance, activation of solenoid 46b will result in the bridging contacts connecting the common contact 23a to circuit contact 21b and also connecting common contact 23m to circiut contact 2112b. Each solenoid 46 controls the axial position of a rod 47, a: to d, each of which extends through the first and second end pieces 12 and 13, and lies adjacent the outer edge of disc 34. The rods 47 have two positions; a normal extended position when the solenoid 46 is not energized, as indicated in FIGURE 1 by the position of rod 470; and a retracted position when the solenoid is energized, as shown by the position of rod 47b. The rods 47 are each encircled by a coil spring 48 compressed between the second end piece 13 and a stop ring 49. Such spring 48 urges the rods 47 into the normal extended position as shown for rod 47a, the spring being compressed when a solenoid 46 is energized. A second coil spring 51 on each rod 47 is compressed between a stop ring 52 and an annular, slidable and rotatable guide 53 shaped to fit into semicircular notches 54 provided in the outer side of the disc 34. Two notches 54 are provided, one being associated with rods 47a and 47b and 'a second notch being associated with rods 47c and 47d.

The guides 53 are slidable toward stop ring 52 against the pressure of coil spring 51 but are prevented from sliding in the opposite direction along rod 47 by a pin '56. Each pin 56 is afiixed to a rod 47 at a position which keeps the guide 53 from contacting the disc 34 when the associated solenoid 46 is not activated. However, when the solenoid 46 is activated, the guide 53 is pressed against the edge of disc 34 and, when the disc is rotated, the guide will roll or slide along the edge of the disc until one of the notches 54 is aligned with the guide, whereupon the guide is pushed into the slot by spring 51. The disc 34 is then prevented from further rotation by the keying or linking action of the guide 53 in the notch 54. To better view the various components of the selector switch, in the figures the switch is shown at a point during the switching process when the guide 53 on rod 46b is engaging a notch 54. Normally, when switching has been accomplished, each of the bridging contacts 36 rest against the one of the contacts 21 and a common contact 23.

To operate the switch, motor 31 and one of the solenoids 46 are energized. In FIGURE 1, solenoid 46b is shown in an energized state. As previously described, the motor first rotates in a direction causing the disc 34 to be retracted from the contacts 21 and 23. When the pressure of the bridging contacts 36 against contacts 23 and 21 is sufliciently low, the disc 34 turns. iWith solenoid 46b energized, the guide 53 is pushed against the edge of disc 34 by spring 51. When the disc 34 turns, the guide 53 rolls or slides along the edge of the disc. If during the rotation of disc 34, the slot 54 is aligned with the guide 53, the guide is urged into the slot and further rotation of disc 34 is prevented. In the example of operation shown in the figures, such locking would occur during the retraction of disc 34 if the bridging contacts 36 had been aligned with either contacts 21c or 21d prior to operation of the switch. However, the pin 42 would strike the stop 43 before such alignment occurs if bridging contacts 36 had been originally aligned with contact 210. In either instance, the rotation of disc 34 is stopped and the retraction of the disc away from the contacts 21 and 23 continues until microswitch 44 is actuated, whereupon the direction of rotation of motor 31 and screw 32 is reversed.

If the disc 34 has been locked by the engagement of guide 53 with slot 54, then the disc 34 is moved axially back toward the contacts 21 and 23 until the bridging contacts 36 press against contacts 21 and 23. A microswitch 57 is provided for stopping motor 31 after the bridging contacts 36 are pressed firmly against contacts 21 and 23, the microswitch being operated by disc 34 as it approaches contacts 21 and 23.

When the rotation of disc 34 has been stopped during retraction by pin 42 resting against stop 43, the disc is free to turn with screw 32 in the opposite direction when the motor 31 reverses. Thus, the disc 34 turns until the slot 54 is aligned with the guide 53', the disc then being prevented from further rotation and being advanced toward the contacts 21b and 23.

The electrical control circuit for obtaining the abovedescribed operation is shown in FIGURE 4.

One end of solenoids 46a to 46 is electrically connected to a first power line conductor 59 carrying one side of volt alternating current power from a line plug 61. The opposite ends of the solenoids 46' are connected to contacts on 'a selector switch 62, the selector arm 63 of which is manually set to select the particular solenoid 36' to be energized. The particular solenoid 46' selected through selector arm 63 is connectable to a second power line conductor 69 from line plug 61 through either a normally open relay contact 64 of a first relay 66 or through a normally open relay contact 67 of a second relay 68. Relay 66 is connected between power lines 59 and 69 through a manual start button 71 and the switch 57'. Disc 34 normally presses against switch 57, closing the circuit between conductor 69 and start button 57, as shown in FIGURE 4. Switch 57 will change position when the disc 34 is retracted from contacts 21 and 23. Thus, by depressing start button 71, first relay 66 is connected to power lines 59 and 69, causing relay 66 to energize and close relay contact 64 and a relay holding contact 72. The relay holding contact 72 connects relay 66 to power line 69 through normally closed switch 44' so that relay 66 continues to be energized after start button 71 is released and switch 57 opens due to the motion of disc 34.

Motor 31', which is a conventional capacitor type single phase motor, has a first winding with running input lead 74 connected to power line 59 and lead 76 connectable to power line 69 through either of relay contact 64 or 67. A second winding in motor 31' is supplied with current shifted in phase relative to current in the first winding, thereby determining the direction the motor turns. The second winding has 'an input lead 78 connected to a phase shifting capacitor 73. The opposite end of such winding has an input lead 77 which is connected through a relay contact 79 to lead 76 when first relay 66 is energized, and to power line 59 when de-energized. Capacitor 73 is connected through a relay contact 81 to power line 59 when second relay 68 is de-energized and to input lead 76 when second relay 68 is energized.

Thus, when the disc 34 is to be retracted from the contacts 21 and 23, the energization of first relay 66 causes the motor 31' to rotate in the appropriate direction. When the switch 44 is operated by disc 34, first relay 66 is deactivated and second relay 68 is activated, causing the motor 31' to reverse direction. The disc 34 is then advanced back toward contacts 21 and 23, with second relay 68 continuing to be energized through holding contact 82 and switch 57'. When the bridging contacts 36 have bridged across gap 27, the disc 34 operates switch 57, deactivating second relay 68. The motor 31 is thus stopped until a subsequent change in the position of the bridging contacts 36 is desired.

Many variations are possible within the spirit and scope of the invention. For instance, additional switch sections, that is, panels 19 with contacts 21 and 23, may be provided to efiect switching of many circuits simultaneously. Therefore, it is not intended to limit the invention except as defined in the following claims.

What is claimed is:

1. A selector switch for high currents, the combination comprising:

(a) a common contact,

(b) a plurality of circuit contacts disposed adjacent said common contact and spaced therefrom by gaps, said circuit contacts and said common contacts being in a single plane,

(c) at least one bridging contactor having a width greater than said gaps,

(d) means consecutively withdrawing and advancing said contactor from and toward said gaps in a direction transverse to said plane, said contactor electrically bridging across a selected one of said gaps from said common contact to one of said circuit contacts when said contactor is fully advanced, and

(e) means aligning said bridging contactor with a selected one of said gaps when said contactor is withdrawn from said circuit contacts and said common contact.

2. A selector switch according to claim 1 wherein said means consecutively withdrawing and advancing said contactor has a rotatable disc to which said contactor is affixed, said disc having a central threaded aperture, a threaded rotatable screw transverse to said plane and engaged with threads in said aperture, means selectively restricting rotational motion of said disc whereby said disc is constrained to move along said screw with rotation thereof.

3. A selector switch according to claim 2 wherein said means withdrawing and advancing said contactor has a reversible motor coupled to said screw, there being a switch operable by engagement with said disc disposed at an outer limit of travel of said disc, operation of said switch reversing the rotational direction of said motor.

4. A selector switch according to claim 2 wherein said common contact has an approximate arcuate shape and is disposed azimuthally with respect to said screw, said circuit contacts extending outwardly from said common contact.

5. A selector switch according to claim 2 wherein said means aligning said contactor with a selected one of said gaps has a plurality of selectively movable locking means, said disc having corresponding means engageable with said locking means during rotation of said disc, said locking means and said engageable means being positioned to align said contactor with a selected one of said gaps.

6. A selector switch according to claim 5 wherein said selectively movable locking means has a plurality of solenoids each having a de-energized position and an energized position, said locking means having a plurality of rods one coupled to each of said solenoids, a guide being disposed on each of said rods, said guides having a position removed from said disc when said solenoid is in a first of said positions, said guide being pressed against said disc when said solenoid is in a second one of said positions, said guide in said second position being linkable with said engageable means of said disc.

References Cited UNITED STATES PATENTS 810,958 1/1906 Lyndon 200-158 1,973,369 9/1934 Burgess 200-7 2,325,860 8/1943 Kizaur 335-72 3,263,145 7/1966 Dexter 318-266 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner U.S. Cl. X.R. 200-158 

